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P0850




DTC P0850-P0852

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

DTC Descriptors
DTC P0850
- Park/Neutral Position (PNP) Switch Circuit

DTC P0851
- Park/Neutral Position (PNP) Switch Circuit Low Voltage

DTC P0852
- Park/Neutral Position (PNP) Switch Circuit High Voltage

Diagnostic Fault Information





Typical Scan Tool Data





Circuit/System Description

The transmission manual shift shaft switch assembly, also known as the Internal Mode Switch (IMS), is a sliding contact switch attached to the manual shift shaft inside the transmission case. The Park/Neutral Position (PNP) Switch is integrated into the IMS and connects to the Transmission Control Module (TCM) lead-frame through a short wire harness. The circuit uses the TCM as a pass-through connector only. The Park/Neutral Signal is sent from the park/neutral switch directly to the engine control module (ECM) and is used for engine start enable.

Conditions for Running the DTC

* Ignition voltage is between 8-18 volts.
* Engine speed is greater than 1000 RPM.

Conditions for Setting the DTC

P0850 and P0851
* The ECM detects the Park/Neutral switch signal equals 0 volts (Park/Neutral) when the IMS reports a Drive range for 0.2 second.
* TP is equal to or greater than 10 percent.
* Engine torque is equal to or greater than 75 Nm (55 lb ft).
* Vehicle speed is equal or greater than 10 km/h (6 mph).

P0852

The ECM detects the Park/Neutral switch signal equals 12 volts (In-Gear) when the IMS reports a Park/Neutral range for 0.2 second.

Action Taken When the DTC Sets

* DTCs P0850, P0851, and P0852 are Type C DTCs.
* The ECM uses IMS Range for engine start-up.

Conditions for Clearing the DTC

DTCs P0850, P0851, and P0852 are Type C DTCs.

Reference Information
Schematic Reference

Automatic Transmission Controls Schematics (Diagrams)
Connector End View Reference

* Component Connector End Views (Connector End Views By Name)
* Inline Harness Connector End Views (Connector End Views By Number)

Description and Operation

Electronic Component Description (Electronic Component Description)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information
Special Tools

DT-47825-20 Adapter Harness

Circuit/System Verification

1. If there are any other transmission DTCs set, diagnose those DTCs first. Refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code (DTC) List - Vehicle).
2. Perform the Range Selector Lever Cable Adjustment (Adjustments) procedure to verify proper adjustment.
3. Ignition ON, observe the scan tool ECM PNP Switch parameter while moving the gear shift lever from Park and through all ranges. The parameter should display Park/Neutral when in Park or Neutral and In-Gear when in Reverse or Drive.
4. Observe the scan tool TCM IMS A/B/C/P parameter while slowly moving the gear shift lever from Park through all ranges. The parameter should match each gear range that is selected. Refer to Transmission Internal Mode Switch Logic (Transmission Internal Mode Switch Logic).
5. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

Note: You must perform the Circuit/System Verification first.

1. Ignition OFF, disconnect the 20-way harness connector at the transmission.
2. Install the DT-47825-20 to the 20-way harness connector to the engine harness.
3. Test for less than 10 ohms between the ground circuit terminal 18 and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

4. Ignition ON, verify the scan tool ECM PNP Switch parameter displays In Gear.

• If not the specified value, test the P/N signal circuit for a short to ground. If the circuit tests normal, replace the engine control module.

5. Connect a 3-amp fused jumper wire between the TCM harness connector terminal 3 and terminal 18. Verify the PNP Switch parameter changes to Park/Neutral.

• If not the specified value, test the P/N signal circuit for an open/high resistance. If the circuit tests normal, replace the engine control module.

6. Ignition OFF, remove the control valve body cover. Refer to Control Valve Body Cover Replacement (Control Valve Body Cover Replacement).
7. Connect the TCM harness connector.
8. Disconnect the IMS connector at the control solenoid valve assembly.
9. Ignition ON, verify the scan tool IMS A/B/C/P parameter displays HI for all four signal circuits.

• If not the specified value, replace the control solenoid valve assembly. Refer to Control Solenoid Valve and Transmission Control Module Assembly Replacement (Service and Repair).

10. Verify the scan tool ECM PNP Switch parameter displays In Gear.

• If not the specified value, replace the control solenoid valve assembly.

11. Connect a 3-amp fused jumper wire between each transmission range signal circuit terminal listed below and the IMS ground circuit, terminal A. Verify the corresponding scan tool IMS A/B/C/P parameter displays LOW when terminals E, D, C, and B are connected to the IMS ground and the ECM PNP Switch parameter displays Park/Neutral when terminal F is connected to ground.

* Switch Signal A terminal E
* Switch Signal B terminal D
* Switch Signal C terminal C
* Switch Signal P terminal B
* PNP Switch Signal terminal F

• If not the specified value, replace the control solenoid valve assembly.

12. If all circuits test normal, replace the IMS.

Repair Instructions

Important:
* Perform the Service Fast Learn Adapts (Programming and Relearning) following all transmission related repairs.

* Before replacing the TCM, perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection (Control Solenoid Valve and Transmission Control Module Assembly Inspection).


Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Control Module References (Programming and Relearning) for ECM or control solenoid valve assembly replacement, setup, and programming
* Range Selector Lever Cable Adjustment (Adjustments)
* Control Valve Body Cover Replacement (Control Valve Body Cover Replacement)
* Manual Shift Detent Lever with Shaft Position Switch Assembly Replacement (Service and Repair)

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